1. Field of the Invention
The present invention relates to a paper sheets feature detector and a paper sheets feature detection method for correctly detecting presence of a watermark, a braille watermark, or a thread, which are important features showing that paper sheets are true paper sheets.
2. Description of the Related Art
Conventionally, there has been a paper sheets processor for automatically judging authenticity of paper sheets such as a banknote inserted from outside, and automatically sorting the paper sheets based on a result of the authenticity judgment.
In determining authenticity of the paper sheets by judgment in the conventional paper sheets processor as above, the authenticity of the paper sheets is generally determined by measuring features inherent in true paper sheets such as a watermark, braille, and a thread by a sensor. However, there has been a problem that it is difficult to know the differences between forged features and true features by the sensor.
For example, regarding a forged watermark pattern and a forged thread drawn by a pencil or the like corresponding to a true watermark pattern and a true thread, and the true watermark pattern and the true thread, the same measurement result is output for both the cases by a light transmissive sensor. Therefore, there is a problem that it is not possible to discriminate true paper sheets from forged paper sheets.
In view of the foregoing conventional actual conditions, it is an object of the invention to provide a paper sheets feature detector and a paper sheets feature detection method for correctly identifying features inherent in true paper sheets.